Habitat complexity reduces the growth of aggressive and dominant brown trout (<Emphasis Type="Italic">Salmo trutta</Emphasis>) relative to subordinates

Animals often prefer areas containing physical structure, and population density often increases with structural complexity, presumably because physical complexity in habitats may offer protection from predators and aggressive competitors. Consequently, increased habitat complexity often results in reduced territory size, lower aggression levels and reduced resource monopolisation by dominants. If behavioural plasticity is limited at early life stages, increased habitat complexity may reduce the relative fitness of aggressive, dominant strategies. Here we tested this hypothesis in an experiment on newly emerged brown trout (Salmo trutta) fry. We show, for the first time, that increased habitat complexity reduces the fitness (i.e. growth rate) of aggressive dominant individuals in relation to subordinates, and that this relation is reversed in simple habitats. Variation in environmental complexity may thus induce fluctuating selective pressures, maintaining behavioural variation in natural populations and allowing subordinate and dominant strategies to coexist.     

Testing common sediment-porewater distribution models for their ability to predict dissolved concentrations of POPs in The Grenlandsfjords, Norway

This study compares in situ observed porewater concentration of persistent organic pollutants (POPs) with predictions by common solid-water phase distribution models. Bottom sediments were sampled in The Grenlandsfjords, Norway, and the interstitial porewater was isolated from the solids by centrifugation and filtration. Both phases were analysed for polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F), polycyclic aromatic hydrocarbons (PAH), and organic carbon. Based on the sediments' solid phase content of POPs, organic carbon, and soot carbon, we used the organic matter partitioning (OMP), and also the soot and organic matter partitioning (SOMP) model to estimate the porewater concentration. The OMP model gave better agreement to observations than the SOMP model for both PCDD/Fs and PAHs. The observed concentration of the PCDD/Fs in the sediments' porewater was much higher than in the deep water of the fjord. The logarithm of the organic matter-water partitioning coefficent (log K(OC)) in the porewater had positive linear regression on the logarithm of the octanol-water partitioning coefficient (log K(OW)). The slope of the regression model was indistinguishable from 1, except for the PAHs as a group which had a slope less than 1. This contrasts to previous studies undertaken in The Grenlandsfjords water column, where the slopes were higher than 1 for PCDD/Fs, and the K(OC) were much higher than the K(OW). One explanation may be that the influence of POPs adsorption to soots decrease because competitive sorption by other compounds in the sediment are higher than in the water column. This indicates that the sorption isotherms for these POPs need better understanding in order to be applicable in both the water column and the porewater.     

Screening of environmental pressure from products in the Swedish railway infrastructure: Implications for strategic environmental management

This paper proposes a method to be used in environmental reviews as an initial tool for estimating upstream environmental pressures from material use in organisations dealing mostly with construction materials. Upstream environmental pressures are often omitted in environmental reviews from organisations and instead tend to be site specific, with a limited life-cycle perspective. This paper uses the Swedish National Rail Authority as a case to present the approach. An energy indicator is used to estimate the environmental pressure of material use.In the studied building project, a small set of products contribute to a major part of the material use and the material-related energy use. The energy use is almost exclusively of nonrenewable energy carriers. The three most important products are all homogenous and non-complex, which makes the energy indicator well suited for the analysis. The organisation can use the results to focus on the most important products and also to see which parts of the organisation contribute to the material-related energy use. Rail traffic in Sweden is almost exclusively from non-fossil-based energy carriers. This highlights the importance of the infrastructure to the overall environmental pressure of the railway. Consequently, if road transport were to shift away from fossil fuels, railways earlier environmental advantages would diminish, since research suggests that railway infrastructure is more energy intensive than road infrastructure.     

Frontal impact dummy kinematics in oblique frontal collisions: evaluation against post mortem human subject test data

OBJECTIVE: Today, a predominant percentage of vehicles involved in car crashes are exposed to oblique or frontal offset collisions. The aim of this study is to evaluate the 50th percentile male Hybrid III, THOR 99, and THOR Alpha dummies by comparing them with the corresponding kinematics of post mortem human subjects (PMHS) in this type of collision. METHODS: The PMHS data include results from oblique frontal collision tests. They include sled tests with near-side and far-side belt geometries at 15 degrees , 30 degrees , and 45 degrees angles. The test subjects were restrained with a three-point lap-shoulder belt and the Delta V was 30 km/h. RESULTS: The results from the Hybrid III and THOR 99 tests showed that, in most of the test, the head trajectories were an average of approximately 0.1 m shorter than those from equivalent PMHS. The Hybrid III and THOR 99 far-side belt geometry tests showed that the belt remained in place longer on the shoulder of the Hybrid III than on the THOR 99 and the THOR Alpha. This was probably due to a stiffer lumbar spine in the Hybrid III and to a large groove in the steel of the superior surface of the Hybrid III shoulder structure. The THOR 99 escaped from the shoulder belt about 40-50 ms earlier than the THOR Alpha. The results from the THOR Alpha tests show that the head trajectory accorded fairly well with the PMHS data, as long as the shoulder belt did not slip off the shoulder. Although the THOR Alpha shoulder escaped the shoulder belt in the 45 degrees far-side belt geometry, the PMHS did not. This may be due to the THOR Alpha shoulder design, with approximately 0.05 m smaller superior and medial shoulder range-of-motion, in combination with a relatively soft lumbar spine. CONCLUSIONS: The THOR Alpha provides head trajectories similar to those of the PMHS under these loading conditions, provided the shoulder belt remains in position on the shoulder. When the shoulder belt slipped off the dummy shoulder, the head kinematics was altered. The shoulder range-of-motion may be a contributing factor to the overall kinematics of an occupant in oblique frontal impact situations where the occupant moves in a trajectory at an angle from that of the longitudinal direction of the car.     

大型动物的种群恢复:大象种群增长的生态学效应

博茨瓦纳北部及其毗邻地区分布着世界上最大的非洲象种群(Loxodonta africana),而在100年前,由于过度捕猎,大象的种群数量极为稀少.     

Margins of agricultural fields as habitats for pollinating insects

The occurrence of pollinating insects in field margins with different vegetation was studied in field experiments. Some margins were widened and vegetation was established by sowing of leguminous plants or was allowed to invade spontaneously. The communities of pollinating insects in reclaimed field margins were compared with those of a margin with a naturally diverse flora and an adjacent pasture. A beehive was placed in the area and the collection of pollen by the honey-bees was followed over the season in order to compare the bees' preferences with the supply of flowering plants available in the different experimental field margins. The sown leguminous plants were very attractive to most insect groups, especially bees and bumble-bees, and their pollen constituted an important part of the bees' total catch. The vegetation established by spontaneous succession especially attracted Syrphidae and other groups of Diptera. Butterflies were found in all vegetation types. It is concluded that small areas with flowering plants can give highly positive effects. The key question is how to avoid weed problems and keep the most attractive plant species with a minimum of cost and effort.     

Aggregation pheromone in Hypogastrura viatica (Collembola)

Summary An animal of the collembolan Hypogastrura viatica isolated on a substrate previously contaminated by individuals of the same species behaves as if it were part of an aggregate. The basic activity decreases by an amount equal to the constant of aggregation. This decrease is due to the response to a stimulus caused by a substance that is discharged onto the substrate by aggregating organisms. This substance seems to be an aggregation pheromone.     

Shopping studies for regional planning

This paper is based on a shopping study carried out by the Department of Geography, University of Utrecht, during 1983. It is concerned with retail planning research for larger regions and starts with a state of the art review of retail planning research in the Netherlands. The aim, in developing a new research strategy, was to reduce time and costs through using computer facilit es for both data handling and data collection. There is discussion of methodology and some outcomes to demonstrate the possibilities of the strategy.     

Data search and environmental hazard assessment for post-seveso chemicals

After the serious accident with a chemical industrial plant at Seveso (Italy) in 1976, the Commission of the European Communities has made a directive on major accidents, usually called the Post-Seveso Guideline. In its annex III, a list of 178 substances is given for which potentially dangerous volumes in case of an accident are defined on the basis of human health criteria. For the implementation of environmental criteria, information on toxicity to aquatic organisms, dilution, and physical behavior in water is needed. A literature search for relevant data on these 178 substances revealed aquatic toxicity data for 116 substances, but only for 87 substances sufficient data were available to make a hazard assessment. As an example, the River Rhine was used to calculate the critical quantities that, after a sudden discharge in the Swiss part, could cause damage at the Dutch part some 800 km downstream. In the absence of a common opinion on the criteria for being a major accident and a serious environmental hazard, the impact of different criteria quantities is discussed. If, for example, in the whole River Rhine a mortality of 5% of the aquatic species is chosen as the criterion for damage to the ecosystem, the critical quantities as mentioned in the EEC directive have to be lowered drastically for the majority of the substances. For 18 substances it could be shown that release of the mentioned quantities would be catastrophic for aquatic life in the whole river.     

Farm cooperation to improve sustainability

In this paper, it is demonstrated that partnership arrangements between farmers might be a way to secure the economic viability of their farms as well as to increase profitability. The article discusses empirical analyses of three different forms of collaboration, with an emphasis on the environmental improvements associated with collaboration. Collaboration between a dairy farm and a crop farm is analyzed in the first case. The results show that potential gains from improved diversification and crop rotation are substantial, and even larger when the collaboration also involves machinery. The second analysis considers external integration between farrowing and finishing-pig operations. Gains from collaboration originate from biological and technical factors, such as improved growth rate of the pigs and better utilization of buildings. Finally, an evaluation of a group of collaborating crop farmers is performed. In this case, the benefits that arise are mainly due to reduced machinery costs and/or gains due to other factors, such as improved crop rotation and managerial/marketing strategies.